1. Field of the Invention
The present invention generally relates to optoelectronic transceiver modules for fiber-optic communications, and in particular optoelectronic transceiver modules which can be conveniently assembled and which are reliable.
2. Description of the Related Art
Optoelectronic transceiver modules provide for bi-directional transmission of data between an electrical interface and an optical data link. The module receives electrically encoded data signals which are converted into optical signals and transmitted over the optical data link. Conversely, the module receives optically encoded data signals which are converted into electrical signals and transmitted onto the electrical interface.
There is a need for a transceiver module which is highly reliable and durable. A print circuit board (PCB), the most important element of the transceiver module, must be enclosed by a shielding housing which absorbs electromagnetic radiation. This ensures that high frequency signals in the transceiver module do not affect external electrical circuits, and that such signals are not affected by external electromagnetic waves. The PCB must be grounded in order to dissipate any static charges which develop on the PCB.
U.S. Pat. No. 5,767,999 discloses a conventional optoelectronic transceiver module. The module comprises a top housing, a bottom housing and a PCB. The PCB is located between the top and the bottom housings. One end of the PCB connects with an electrical connector, and the other end of the PCB connects with optoelectrical components which have leads soldered to the PCB. Unfortunately, the PCB is fixed by plastic positioning dowels. Therefore the housing cannot be effectively connected to a grounding circuit of the PCB. There is no reliable grounding connection between the housing and the PCB. Any static charges on the housing cannot be timely dissipated to ground, which adversely affects the performance of the transceiver module. Furthermore, assembly of this conventional transceiver module is unduly laborious.
Another conventional optoelectronic transceiver module is disclosed in U.S. Pat. No. Re. 36,820. A PCB and other optoelectronic components are placed in a rectangular box. By injecting potting material into the box, the PCB and the optoelectronic components can be enclosed. The enclosure of the transceiver module fixes and protects the PCB. However, potting material is expensive and unduly troublesome to use. Furthermore, the structure does not provide satisfactory grounding connection between the PCB and the box. Thus the box does not effectively dissipate buildup of electrostatic charge thereon, and does not provide optimal electromagnetic shielding.
In view of the above, there is a need for a transceiver module which can easily and securely fix the PCB in a metal housing while simultaneously effectively establishing a grounding path between the PCB and the metal housing.
Therefore, one object of the present invention is to provide a transceiver module which can easily and securely fix a PCB in a housing.
Another object of the present invention is to provide a transceiver module with an effective grounding path between a PCB and a housing.
The transceiver module of the present invention comprises a housing, an optoelectronic subassembly, a receptacle, a chassis and a PCB. The optoelectronic subassembly is received in the receptacle. Conductive leads of the optoelectronic subassembly are soldered to the PCB. The chassis is attached to the PCB with screws, and accommodates and protects the PCB. The housing comprises a top housing and a bottom housing. The top housing is attached to the chassis and the receptacle. The top housing and the bottom housing are attached together, enclosing therein the receptacle, the chassis and the PCB.